> ## Documentation Index
> Fetch the complete documentation index at: https://docs.radion.app/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP

> Connect an AI client to the Radion RPC node over MCP. Read-only, authenticated with your paid Radion API key.

The RPC node exposes an [MCP](https://modelcontextprotocol.io) endpoint at `https://rpc.radion.app/mcp`. An AI client (Claude Code, Codex, Cursor, and others) can call the node with structured, **read-only** tools instead of hand-written JSON-RPC.

It is the same node and the same key as the [RPC](/rpc/overview). MCP is a **paid** feature; the free plan gets a `403 Forbidden`.

## Endpoint

```
https://rpc.radion.app/mcp
```

Transport is **SSE** (Server-Sent Events) over HTTPS. Authenticate with your API key in the `X-API-Key` header, same as the RPC.

## Connect a client

Add the endpoint to your MCP client config. Set your API key as a header.

```json title="Claude / Cursor mcp config" theme={null}
{
  "mcpServers": {
    "radion-rpc": {
      "url": "https://rpc.radion.app/mcp",
      "headers": { "X-API-Key": "YOUR_API_KEY" }
    }
  }
}
```

Once connected, the client lists the node's tools and can call them on its own.

## What it exposes

Read-only tools over the Polygon node, including:

* **Ethereum standard** — `eth_blockNumber`, `eth_getBlockByNumber`, `eth_getBalance`, `eth_call`, `eth_getLogs`, `eth_getTransactionReceipt`.
* **Erigon** — `erigon_getBlockByTimestamp`, `erigon_getBalanceChangesInBlock`, and more.
* **Otterscan tracing** — `ots_getInternalOperations`, `ots_traceTransaction`, `ots_searchTransactionsAfter`.

No write tools. Nothing that submits a transaction or changes state.

## Limits

* `eth_getLogs` block ranges are capped, same as the [RPC](/rpc/methods#limits-on-eth_getlogs). Keep ranges small and filter by address and topic.
* Heavy tracing tools may be capped or restricted on lower tiers.

## Get access

MCP is on the **Starter**, **Pro**, and **Enterprise** plans. Use the same key as the REST API and RPC. See [Authentication](/rpc/authentication).

<Note>
  Looking for Polymarket market and orderbook data over MCP instead of the raw
  node? See the [Radion MCP server](/ai/mcp).
</Note>